<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //第一题
        var [x=1]=[undefined]
        var [y=1]=[null]
        console.log(x,y)  //1  null

     //第七题

        function f1(){
            let n=5;
            if(true){
                let n=10;
            }
            console.log(n)
        }
        f1()  //5
    </script>
</body>
</html>